The present invention relates to a rolling steel door, and more particularly to a light structure of rolling steel door, which needs less storage space when rolled up.
FIGS. from 7 through 10 show a rolling steel door 2 according to the prior art. This structure of rolling steel door comprises a plurality of solid metal transverse rods 23, a plurality of sleeves 22 respectively sleeved onto the metal transverse rods 23, and a plurality of links 21 respectively coupled to the metal transverse rods 23 to hold the metal transverse rods in parallel. The links 21 are oblong metal plates, each comprising two remote ends 211, and two coupling holes 212 respectively formed on the two remote ends 211 and coupled to a respective metal transverse rod 23. The links 21 are arranged in sets. Each set of links 21 include two pairs of first links respectively coupled between two adjacent pairs of metal transverse rods, and one second link coupled between the adjacent metal transverse rods of the two adjacent pairs of metal transverse rods being connected to the pairs of first links and retained between the pairs of first links. This structure of rolling steel door is still not satisfactory in function. The drawbacks of this structure of rolling steel door is outlined hereinafter.
1. Because the links 21 are flat members, the contact area between each coupling hole 212 and the corresponding metal transverse rod 23 is limited, and the metal transverse rods 23 tend to be damaged by the coarse border area of each coupling hole 212. Because the metal transverse rods 23 tend to be damaged by the coarse border area of each coupling hole 212, the metal transverse rods 23 must have a solid structure. PA0 2. Because the metal transverse rods 23 are solid metal rods, the manufacturing cost and total weight of the rolling steel door are high, and a high capacity of motor, which consumes much electric power, must be used to move the rolling steel door. In case of a power failure, much effort must be employed to take up the rolling steel door manually. PA0 3. Because the links 21 are flat members, they tend to be forced to vibrate when moving taking up or letting off the rolling steel door, thereby causing a high noise level to be produced (see FIG. 9). PA0 4. Because the links 21 are flat members, the rolled diameter D1 of the rolling steel door cannot be minimized when rolled up about a spooling structure 213, i.e., a spacious receiving chamber must be provided to receive the rolling steel door when the rolling steel door is rolled up.